According to the debug log, the only difference is the sync row 0 vs 1.

Update

Hum, that is interesting… A basic reinstallation of DAVdroid 1.11.3-gplay was not helping, but when I have installed 1.9.9-gplay, the sync worked as expected. Then I’ve installed 1.11.2-gplay and it worked too. Then I have installed 1.11.3-gplay back, and so it has also worked.

I am confused now The good point that it is working now for me. (without me cleaning the brute force attempts table, see below)

If you anyone is having the same issue while using Nextcloud or Owncloud, please try cleaning your brute force attempts table from it:

@rfc2822 AFAIR, there was Android OS update quiet some time ago, longer before I started to see the error message. The first time I’ve got the error message was the last week as I was traveling to Greece, so the timezone was shifted by +1 hour. That was the time I started to see the error message. Also, it might be worth mentioning, I was making a phone factory reset just a day before I traveled to Greece last week.

I had the same exception all of a sudden this afternoon. I updated DAVdroid to 1.11.4-beta4-ose (from F-Droid) yesterday evening, syncing flawlessly during the entire morning. Disabling and enabling claendars in DAVdroid didn’t make any difference. I also deleted the calendar storage data from the Android settings > apps, same error occurred.

Hum, that is interesting… A basic reinstallation of DAVdroid 1.11.3-gplay was not helping, but when I have installed 1.9.9-gplay, the sync worked as expected. Then I’ve installed 1.11.2-gplay and it worked too. Then I have installed 1.11.3-gplay back, and so it has also worked.

That’s basically what seems to have helped also for me: I uninstalled DAVdroid 1.11.1-ose (the oldest version F-Droid is offering) and synced my calendars. Then I updated to 1.11.2-ose and synced, no problem occurred. Finally I updated to 1.11.4-beta4-ose and up until now sync works like a charm.

I’m also experiencing this bug for the last few days. No major update of Android for the last few weeks.
I noticed this bug was triggered when I created/updated an event on my calendar (stored on a private Owncloud).
Is there a way to detect which event could have triggered the bug?

I also encounter the same issue while syncing calendars for 2-3 days. At first it was completely hidden, i.e. no visual information just some short vibrations which I assume to be the indicator for this problem. Manual sync gives the same error as above. I am using android 8.0 on Moto Z. There has not been any system update for a while, so this can’t be the reason! I am using the latest DavDroid (1.11.5-gplay). My backend is latest nextcloud 13.0.4. Do you need any additional information to trace the error? Thunderbird calendar syncs flawlessly…
christian

I also experience said problem on Android 8.0.0 (Oneplus 3) with DAVdroid 1.11.5-gplay. The server side backend is Sabre/DAV (like with Nextcloud, Baikal, etc.), though I think that is isn’t a server-side problem (by the information shown in this thread).

@rfc2822 I can reproduce the exception arbitrarily many times by syncing events to the device that have not existed on the device before. The issue occurs specifically for full-day events (that don’t even have any time zone information defined), like the one listed below. Even events I have created on my device, synced to the server and after that forced to resync to the device (by turning the calendar off and on again) face this kind of issue. Maybe this helps for reproducing/debugging the exception?

I will also take a look at the issue tracker of ical4j and provide the same information there.

I also experience said problem on Android 8.0.0 (Oneplus 3) with DAVdroid 1.11.5-gplay. The server side backend is Sabre/DAV (like with Nextcloud, Baikal, etc.), though I think that is isn’t a server-side problem (by the information shown in this thread).

I just tried to reinstall DAVdroid, which magically fixed the problem. Maybe the information I provided will still help in fixing the original issue.

This following is a bit of a guess, but this problem only just happened for me, whereas my update to Android 8.0.0 was a while ago - and I have thought of something else which is relevant. (That said, I have also installed some more minor updates from Samsung, fairly recently, though these haven’t changed the displayed version numbers of anything, and I /think/ this was also longer ago than the problem starting…)

Anyway, one thing I have done with my calendars recently - but haven’t ever done with them before - is to change the calender of an event. Google Calendar, which I mainly use, has never allowed this: after an event is first created, you have to delete the event and re-create it in a different calendar. But the Samsung Calendar app (which looks as if it is based on Google Calendar, though I don’t know for sure) /does/ allow you to change the calendar of an event. I only noticed that the Samsung Calendar had this option recently, and I only used it even more recently. Is there any chance that doing this is what triggers the issue?

(I haven’t had a chance to test this further yet, as I haven’t yet had the time to reset my calendar storage to test this, as I’d want to try to figure out all my recent calendar changes since the error started popping up, so as not to lose them, first!)

@mjsbeaton thanks for your input on this! If you find a way to really re-produce the error we’d be very “happy”. Unfortunately it is happening only very occasionally for users, and we don’t think it’s a special issue of calendar apps. We /think/ it may has to do with some sort of caching in Android 8.0.0. It also never has happened other than on 8.0.0 - so maybe it was an issue that is already fixed on 8.1 and some manufacturers have had the pity to start with an early build of 8.0.0 and now continue to deliver builds containing this bug.

Okay, on further testing, it doesn’t seem to be that. I’ve deleted and reinstalled DAVdroid, and it’s actually started working. (I initially saw a DAVdroid permissions notification pop up, and thought I was seeing a repeat of the error - but no, it’s all working!) Then I’ve changed an event’s calendar and it’s still working. I should have tested further before posting - sorry. Will post again if I find anything repeatable of course. Thanks!